Battery and Inverter Calculator

Estimation of backup time, required battery capacity, and inverter power, considering surge currents, efficiency, battery type, and temperature.

Total Energo LLC provides free measurements and equipment selection for your specific backup needs when purchasing from our store.

Step 1

Appliances

Select typical appliances or add your own. Enter wattage from the device label.

 
Name
Power, W
Qty
Runtime, %
Surge, ×
 
 

«Runtime, %» indicates the percentage of time the appliance is actively drawing power.

Many devices don't run constantly. For example, a refrigerator's compressor runs about a third of the time. If calculated as a continuous 150W load, the result would be overestimated, leading you to buy unnecessary battery capacity.

Surge, × — starting current multiplier (motors/compressors: 3–7, electronics/heaters: 1).
Step 2

System and Battery

 
Auto-filled based on battery type
Add capacities for parallel batteries
Cold reduces usable capacity
Typically 10–60 W depending on model
Charger / MPPT / Inverter charging
Auto-calculates on change
Result

Estimated values. Cross-reference with manuals for critical systems.

Battery backup time
—
 
Usable battery energy
— kWh
Considering DoD and temperature
Capacity required for backup
— Ah
— kWh (with reserve)
Recommended inverter
— W
≈ — VA, peak at least — W
Load: average / continuous max
— / — W
Surge peak: — W
Battery charging time
—
From DoD to full (Charge eff. —%)
Battery current: avg / max
— / — A
Peak with surge: — A
Battery fuse (estimate)
— A
≈ 125% of max current
Discharge rate (C-rate)
— C
Allowed up to — C for this type
 

Reference: Battery Types

Battery Type Rec. DoD, % Max Discharge, C Cycles (est.) Charge Eff., %

Warning

Calculations are estimates and should not be taken as 100% precise. The calculator uses average reference data. Real-world performance depends on actual device specs, battery age and condition, temperature, installation quality, and usage patterns.

Accurate figures are only possible after measurements by a specialist using professional equipment. Do not make purchasing or installation decisions based solely on this calculation.